This study will compare 3 monoclonal Pneumocystis carinii immunofluorescence test kits for sensitivity and specificity in detection of Pneumocystis carinii in respiratory specimens. The three kits are: 1) Monoclonal antibody (MAB) Indirect Fluorescent Antibody (NIH); 2) MAB Direct Fluorescent Antibody (Genetic Systems Corporation, Seattle, Washington, 98121), and 3) MAB Indirect Fluorescent Antibody; Fluoroslide Pneumocystis carinii (Disease Detection International, IME, Irvine, California). Induced sputums and bronchial lavages from AIDS patients as well as non-AIDS patients will be tested for the presence of Pneumocystis carinii. The patient population will include pediatric as well as adult patients to determine sensitivity and specificity of the different commercial kits to see which one is best to use for detecting Pneumocystis carinii in respiratory specimens.